CN114945744A

CN114945744A - Control device for internal combustion engine

Info

Publication number: CN114945744A
Application number: CN202180009036.4A
Authority: CN
Inventors: 押领司一浩; 赤城好彦; 小祝隆太郎
Original assignee: Hitachi Astemo Ltd
Current assignee: Hitachi Astemo Ltd
Priority date: 2020-03-30
Filing date: 2021-01-15
Publication date: 2022-08-26
Anticipated expiration: 2041-01-15
Also published as: JP7291656B2; CN114945744B; JP2021161872A; US20230079934A1; WO2021199576A1

Abstract

The invention provides a control device for an internal combustion engine, which can respectively and efficiently raise the temperature of a catalyst and the temperature of cooling water compared with a conventional waste heat control device. The invention is a control device that acquires a cooling water temperature (T _ cw) and a catalyst temperature (T _ cat) of an exhaust system to control an ignition timing (theta) of an internal combustion engine. The control device executes cooling water warming control for increasing the energy distribution from the internal combustion engine to the cooling water when the cooling water temperature (T _ cw) is equal to or lower than a 1 st threshold value, and catalyst warming control for increasing the energy distribution from the internal combustion engine to the exhaust gas when the catalyst temperature (T _ cat) is equal to or lower than a 2 nd threshold value.

Description

Control device for internal combustion engine

Technical Field

The present disclosure relates to a control device for an internal combustion engine.

Background

Conventionally, an invention related to an engine exhaust heat control device that controls the amount of exhaust heat of an engine in accordance with a heat utilization demand has been known (see patent document 1 below). The exhaust heat control device for an engine described in patent document 1 is applied to an exhaust heat recycling system for recycling exhaust heat of the engine, and controls the amount of exhaust heat of the engine in accordance with a required amount of heat given by a heat utilization demand. The conventional exhaust heat control device is characterized by including a superimposition amount control means, an ignition control means, and an exhaust heat control means (the abstract of the document, paragraph 0008, claim 1, and the like).

The overlap amount control means controls the overlap amount between the valve opening period of the intake valve and the valve opening period of the exhaust valve of the engine according to the engine operating state. The ignition control unit controls the ignition timing of the engine at a maximum efficiency timing to achieve a maximum fuel efficiency in each engine operating state. In a case where the required heat amount cannot be satisfied, the exhaust heat control unit executes overlap increase control of changing the overlap amount toward an increase side and ignition advance control of changing the ignition timing toward an advance side in comparison with the maximum efficiency timing corresponding to the overlap amount after the change toward the increase side.

The conventional exhaust heat control device changes the overlap amount to the increase side when the required heat amount cannot be satisfied as in the above-described configuration, and changes the ignition timing to the advance side in comparison with the maximum efficiency timing (MBT or its vicinity) corresponding to the overlap amount after the change to the increase side. This makes it possible to perform waste heat control in accordance with the heat utilization requirement while suppressing deterioration of fuel efficiency as much as possible (paragraph 0009 of the document, etc.).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-074800

Disclosure of Invention

Problems to be solved by the invention

The above-described conventional exhaust heat control device achieves a certain effect mainly in the case of recovering exhaust heat from the engine using the coolant. However, the conventional exhaust heat control device described above has a problem that it cannot cope with a situation in which the operation frequency of the engine is low and the temperature of the catalyst and the temperature of the coolant included in the exhaust system of the engine are both lowered.

The present disclosure provides a control device for an internal combustion engine capable of increasing the temperature of a catalyst and the temperature of cooling water more efficiently than the conventional exhaust heat control device described above.

Means for solving the problems

One aspect of the present disclosure is a control device for an internal combustion engine that acquires a cooling water temperature and a catalyst temperature of an exhaust system to control an ignition timing of the internal combustion engine, wherein a cooling water heating control that increases an energy distribution from the internal combustion engine to cooling water when the cooling water temperature is equal to or lower than a 1 st threshold value and a catalyst heating control that increases an energy distribution from the internal combustion engine to exhaust gas when the catalyst temperature is equal to or lower than a 2 nd threshold value are executed.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the above aspect of the present disclosure, it is possible to provide a control device for an internal combustion engine capable of increasing the temperature of a catalyst and the temperature of cooling water more efficiently than in the conventional exhaust heat control device.

Drawings

Fig. 1 is a block diagram showing an embodiment 1 of a control device for an internal combustion engine according to the present disclosure.

Fig. 2 is a block diagram showing a relationship between the control device of fig. 1 and the internal combustion engine.

Fig. 3 is a block diagram showing a configuration of the control device of fig. 1.

Fig. 4 is a functional block diagram of the control device of fig. 1.

Fig. 5 is a graph illustrating the energy distribution of the internal combustion engine of fig. 1.

Fig. 6 is a flowchart illustrating a process performed by the function of calculating the correction amount of the ignition timing shown in fig. 4.

Fig. 7 is a graph showing a state of the internal combustion engine in the process of fig. 6.

Fig. 8 is a flowchart illustrating a flow of processing of the control device of fig. 1.

Fig. 9 is a graph showing the result of the processing shown in fig. 8.

Fig. 10 is a flowchart illustrating processing in the ignition timing correction function of fig. 4.

Fig. 11 is a graph illustrating the energy distribution of the internal combustion engine under the process of fig. 10.

Fig. 12 is a functional block diagram showing embodiment 2 of the control device for an internal combustion engine according to the present disclosure.

Fig. 13 is a flowchart illustrating processing performed by the torque correction function of fig. 12.

Fig. 14 is a graph showing the result of the processing of fig. 13.

Fig. 15 is a graph showing the results of the processing of fig. 13.

Fig. 16 is a functional block diagram showing embodiment 3 of the control device for an internal combustion engine according to the present disclosure.

Fig. 17 is a flowchart showing a process in the function of calculating the distribution of ignition correction shown in fig. 16.

Fig. 18 is a flowchart showing a process in the function of calculating the ignition correction amount shown in fig. 16.

Fig. 19 is a graph showing the results of the processing shown in fig. 17 and 18.

Detailed Description

Next, an embodiment of the control device for an internal combustion engine according to the present disclosure will be described with reference to the drawings.

[ embodiment 1]

Fig. 1 is a block diagram showing an embodiment 1 of a control device for an internal combustion engine according to the present disclosure. The control device 10 of the present embodiment is mounted in a vehicle such as a series hybrid vehicle, for example, and controls the engine 1 as an internal combustion engine.

The vehicle includes, for example, an engine 1, a generator 2, inverters 3A and 3B, a power storage device 4, a motor 5, a vehicle control device 6, an accelerator pedal 7, and a control device 10 for an internal combustion engine. The vehicle includes, for example, a crank angle sensor S1, an accelerator opening degree sensor S2, and a battery voltage sensor S3. The engine 1 is, for example, a spark ignition engine, such as a four-cylinder gasoline engine. The generator 2 is coupled to a crankshaft 1a of the engine 1, and generates electric power by rotation of the crankshaft 1 a.

The power storage device 4 is connected to a generator via an inverter 3A, and is connected to a motor 5 via an inverter 3B, for example. The power storage device 4 includes, for example, a plurality of secondary batteries, and is charged with generated power supplied from the generator 2 via the inverter 3A or regenerative power supplied from the motor 5 via the inverter 3B. The power storage device 4 supplies electric power to the motor 5 via the inverter 3B to drive the motor 5. The motor 5 is driven by electric power supplied from the power storage device 4 via the inverter 3B, and rotates wheels, not shown, to run the vehicle.

The vehicle control device 6 is connected to the crank angle sensor S1, the accelerator opening sensor S2, the battery voltage sensor S3, and the control device 10 for the internal combustion engine so as to be able to communicate information. The crank angle sensor S1 detects the rotation angle of the crankshaft 1a of the engine 1. The accelerator opening sensor S2 detects an accelerator opening, which is an amount of depression of the accelerator pedal 7. Battery voltage sensor S3 measures the internal voltage of power storage device 4. The vehicle control device 6 receives signals of the detection results and the measurement results from the sensors S1, S2, and S3.

The vehicle control device 6 calculates a required torque based on an operation of the driver of the vehicle based on a detection result of the accelerator opening degree input from the accelerator opening degree sensor S2. That is, the accelerator opening degree sensor S2 may be used as a required torque sensor that detects a required torque for the engine 1 or the motor 5. Further, the vehicle control device 6 calculates the state of charge or the remaining charge amount of the power storage device 4 based on the detection result of the internal voltage of the power storage device 4 input from the battery voltage sensor S3. The vehicle control device 6 calculates the rotation speed of the engine 1 based on the detection result of the rotation angle of the crankshaft 1a input from the crank angle sensor S1.

Further, the vehicle control device 6 calculates the optimum operation amounts of the respective devices, such as the required output of the engine 1 and the required output of the power storage device 4, based on the required torques based on the inputs from the sensors S1, S2, and S3 and the operating state of the vehicle. The vehicle control device 6 outputs a control signal including the calculated required output of the engine 1 to the control device 10 of the internal combustion engine. The control device 10 for the internal combustion engine controls the engine 1 in accordance with a control signal including a requested output of the engine 1 input from the vehicle control device 6.

Fig. 2 is a block diagram showing a relationship between the control device 10 of the internal combustion engine of fig. 1 and the engine 1 as an internal combustion engine as a control target thereof.

As shown in fig. 2, the engine 1 includes, for example, an intake pipe 1b, an air flow sensor S4, an electronically controlled throttle valve 1c, and an intake air temperature sensor S5, in addition to the crankshaft 1a and the crank angle sensor S1 of fig. 1. The engine 1 includes, for example, four cylinders 1d, an injector 1e, an ignition coil 1f, a cooling water temperature sensor S6, and a knock sensor S7. The engine 1 includes, for example, an exhaust pipe 1g, a three-way catalyst 1h, an air-fuel ratio sensor S8, and an exhaust gas temperature sensor S9.

The intake pipe 1b is configured to allow air flowing into each cylinder 1d of the engine 1 to flow therethrough, for example. The airflow sensor S4 is provided at an appropriate position in the intake pipe 1b, for example, and measures the flow rate of air flowing through the intake pipe 1b and outputs the measurement result to the control device 10. The electronically controlled throttle 1c is controlled by, for example, the control device 10, and adjusts the flow rate of air flowing into each cylinder 1 d. The intake air temperature sensor S5 measures the temperature of the air flowing through the intake pipe 1b, for example, and outputs the measurement result to the control device 10.

The injector 1e is, for example, a fuel injection device or an in-cylinder direct injection injector provided in each cylinder 1d (#1 to #4) and injecting fuel into a combustion chamber of each cylinder 1 d. The ignition coil 1f generates a high voltage for discharging by an ignition plug provided in each cylinder 1d, for example. The cooling water temperature sensor S6 is provided at an appropriate position of the cylinder head of the engine 1, for example, and measures the cooling water temperature of the engine 1 and outputs the measurement result to the control device 10. The knock sensor S7 is provided, for example, in a cylinder block of the engine 1, detects vibration of the engine 1, and outputs the detection result to the control device 10.

The exhaust pipe 1g is through which exhaust gas discharged from each cylinder of the engine 1 flows, for example. The three-way catalyst 1h is provided at an appropriate position of the exhaust pipe 1g, for example, and purifies the exhaust gas flowing through the exhaust pipe 1 g. The air-fuel ratio sensor S8 is provided upstream of the three-way catalyst 1h in the exhaust pipe 1g in the flow of exhaust gas, for example, measures the air-fuel ratio of the exhaust gas, and outputs the measurement result to the control device 10. The exhaust gas temperature sensor S9 is provided upstream of the three-way catalyst 1h in the exhaust pipe 1g, for example, and measures the temperature of the exhaust gas and outputs the measurement result to the control device 10.

The control device 10 of the internal combustion engine according to the present embodiment is an Electronic Control Unit (ECU) equipped with a processing device such as a CPU, a storage device such as a memory, a signal input/output unit, and the like, for example. The control device 10 inputs measurement results from, for example, the aforementioned crank angle sensor S1, air flow sensor S4, intake air temperature sensor S5, cooling water temperature sensor S6, knock sensor S7, air-fuel ratio sensor S8, and exhaust gas temperature sensor S9. The control device 10 inputs the measurement result of the accelerator opening degree sensor S2, for example, via the vehicle control device 6 described above.

Further, the control device 10 receives from the vehicle control device 6 the required torque of the engine 1 calculated by the vehicle control device 6 based on the measurement result of the accelerator opening degree sensor S2. The control device 10 also receives from the vehicle control device 6 the rotation speed of the engine 1 calculated by the vehicle control device 6 based on the measurement result of the crank angle sensor S1. The required torque and the rotation speed of the engine 1 may be calculated by the controller 10 based on the measurement result of the accelerator opening sensor S2 and the measurement result of the crank angle sensor S1.

The control device 10 calculates the operating state of the engine 1 based on information input from the above-described sensors, for example. Further, the control device 10 calculates main control parameters of the engine 1 including the ignition time of the engine 1, the throttle opening degree, the fuel injection amount, and the like.

The fuel injection amount calculated by the control device 10 is converted into, for example, a valve opening pulse signal, and is output from the control device 10 to the injector 1 e. The ignition timing calculated by the control device 10 is converted into an ignition signal, for example, and is output from the control device 10 to the ignition coil 1 f. The throttle opening calculated by the control device 10 is converted into a throttle drive signal, and is output from the control device 10 to the electronically controlled throttle 1 c.

The electronically controlled throttle 1c passes air at a throttle opening corresponding to a throttle drive signal input from the control device 10. The air having passed through the electronically controlled throttle valve 1c flows in the intake pipe 1b and flows into the combustion chamber of each cylinder 1d via an intake valve, not shown. The injector 1e injects fuel into the combustion chamber of each cylinder 1d in accordance with a valve opening pulse signal input from the control device 10. Thereby, an air-fuel mixture is generated in the combustion chamber of each cylinder 1 d.

The ignition coil 1f generates a high voltage for discharging by an ignition plug based on an ignition signal input from the control device 10. As a result, the air-fuel mixture is combusted in the combustion chamber of each cylinder 1d, a piston in each cylinder 1d, not shown, is pushed down, and the engine 1 generates a driving force to rotate the crankshaft 1 a. The exhaust gas discharged from the combustion chamber of each cylinder 1d after the combustion of the air-fuel mixture flows through the exhaust pipe 1g, is purified by the three-way catalyst 1h, and is discharged to the outside.

Fig. 3 is a block diagram showing an example of the configuration of the control device 10 for the internal combustion engine of fig. 1. The control device 10 includes, for example, an input circuit 11, an input/output port 12, a RAM13, a ROM14, a CPU15, an ignition control unit 16, and a throttle control unit 17.

The input circuit 11 inputs, for example, a required torque τ _ req and a rotation speed R _ eng of the engine 1 calculated by the vehicle control device 6 and outputted from the vehicle control device 6. The input circuit 11 receives the throttle opening P _ thr from the electronically controlled throttle 1c, the exhaust gas temperature T _ exh from the exhaust gas temperature sensor S9, and the cooling water temperature T _ cw from the cooling water temperature sensor S6, for example.

Although not shown in fig. 3, the input circuit 11 receives an input of the air flow rate from the air flow rate sensor S4, the intake air temperature from the intake air temperature sensor S5, the detection result of the vibration of the engine 1 from the knock sensor S7, and the air-fuel ratio from the air-fuel ratio sensor S8, for example. In this manner, the input circuit 11 can input information other than the information shown in fig. 3. The input circuit 11 outputs the input information to an input port of the input/output port 12.

The RAM13 acquires and temporarily holds information output from the input circuit 11 via the input/output port 12. The ROM14 stores various control programs and data.

The CPU15 executes various control programs stored in the ROM14, thereby executing various arithmetic processes using the information held in the RAM 13. Through these various arithmetic processes, the CPU15 calculates various control parameters including the workload of various actuators of the vehicle and stores the control parameters in the RAM 13.

Further, the CPU15 outputs various control parameters held in the RAM13 to various drive circuits including the ignition control portion 16 and the throttle control portion 17 via the output port of the input/output port 12. The control device 10 may include a drive circuit other than the ignition control unit 16 and the throttle control unit 17. These drive circuits may be provided outside the control device 10.

The ignition control section 16 outputs an ignition signal S _ ign to the ignition coil 1f in accordance with a control parameter input via an output port of the input/output port 12. The throttle control portion 17 outputs a control signal S _ thr of the throttle opening degree to the electronically controlled throttle valve 1c in accordance with the control parameter input via the output port of the input/output port 12.

Further, the CPU15 executes arithmetic processing using the detection result of the vibration of the engine 1 input from the knock sensor S7 to the input circuit 11 and held in the RAM13 via the input/output port 12, thereby detecting the occurrence of knocking. The CPU15 estimates the catalyst temperature T _ cat, which is the temperature of the three-way catalyst 1h of the exhaust system, by executing arithmetic processing using the exhaust gas temperature T _ exh input from the exhaust gas temperature sensor S9 to the input circuit 11 and held in the RAM13 via the input/output port 12.

Fig. 4 is a functional block diagram of the control device 10 of the internal combustion engine of fig. 1. The control device 10 has, for example, a function F1 of calculating the ignition timing correction amount Δ θ and a function F2 of correcting the ignition timing. The functions F1 and F2 of the control device 10 can be realized by the CPU15 executing a control program stored in the ROM14, for example.

The function F1 for calculating the ignition timing correction amount Δ θ receives as input the required torque τ _ req and the rotation speed R _ eng of the engine 1, the cooling water temperature T _ cw, the catalyst temperature T _ cat, and the ignition timing θ, for example. Function F1 calculates ignition time correction amount Δ θ from these inputs. Function F2 for correcting ignition timing calculates corrected ignition timing θ' using ignition timing θ and ignition timing correction amount Δ θ as inputs.

Fig. 5 is a graph illustrating the energy distribution of the engine 1 as the internal combustion engine of fig. 1. In the graph of fig. 5, the vertical axis represents the energy E, and the horizontal axis represents the ignition time θ of the engine 1.

In fig. 5, the energy distribution η _ cw from the engine 1 to the cooling water is indicated by a dotted line, the energy distribution η _ exh from the engine 1 to the exhaust gas is indicated by a broken line, and the energy distribution η _ i from the engine 1 to the motive power is indicated by a solid line. The energy distributions η _ i, η _ cw, and η _ exh are ratios to the total energy generated by the engine 1, for example.

Here, advancing the ignition time θ of the engine 1 is synonymous with decreasing the crank angle in the ignition time θ. Further, retarding the ignition time θ of the engine 1 is synonymous with increasing the crank angle in the ignition time θ. Therefore, the correction of the ignition timing θ in which the ignition timing correction amount Δ θ is negative is hereinafter referred to as advance correction, and the correction of the ignition timing θ in which the ignition timing correction amount Δ θ is positive is hereinafter referred to as retard correction.

The energy distribution η _ i to the motive power of the engine 1 is maximized at the optimal ignition time θ o, and is reduced when the ignition time θ is corrected in advance or corrected in retard from the optimal ignition time θ o. Further, the larger the ignition time correction amount Δ θ for the advance correction, the more the energy distribution η _ cw from the engine 1 to the coolant increases. The larger the correction amount of the retard correction is, the more the energy distribution η _ exh from the engine 1 to the exhaust gas increases. That is, in the engine 1, the energy distribution η _ i, η _ cw, η _ exh to the power, the cooling water, and the exhaust gas changes according to the ignition time θ.

Fig. 6 is a flowchart illustrating the calculation process in function F1 for calculating ignition time correction amount Δ θ in fig. 4. Fig. 7 is a graph showing a state of the engine 1 in the processing flow of fig. 6.

In fig. 7, the horizontal axis of each graph represents time T, and the vertical axis of each graph represents, from top to bottom, the Operating (ON) and OFF (OFF) states of the engine 1, the ignition time θ, the torque τ of the engine 1, and the cooling water temperature T _ cw. In each of the graphs other than the graphs showing the operation and the shut-off of the engine 1 in fig. 7, the states of the engine 1 in the setting C1 and the setting C2 of the advanced control performed by the control device 10 of the present embodiment, which are comparative forms using the conventional control device, are shown by a solid line, a dotted line, and an alternate long and short dash line.

As shown in fig. 7, when the required torque τ _ req is input at time t0, the engine 1 is started and operated. Here, in order to easily understand the operation of the engine 1, a case where the required torque τ _ req is fixed will be described. In a comparative mode using a conventional control device, when the engine 1 is started at time t0, the throttle opening P _ thr and the ignition timing θ are set so as to satisfy the required torque τ _ req.

Thus, in the graph of the ignition time θ and the graph of the torque target value τ in fig. 7, the ignition time θ and the torque τ are maintained substantially constant in the comparative form shown by the solid line. In addition, in the operating state in which the engine 1 is operating, energy is supplied from the engine 1 to the cooling water in the form of heat. Thus, in the graph of the cooling water temperature T _ cw in fig. 7, the cooling water temperature T _ cw gradually increases in the comparative form shown by the solid line.

On the other hand, in the control device 10 of the present embodiment, when the engine 1 is started at time t0, the process flow shown in fig. 6 is started by the function F1 of fig. 4 that calculates the ignition time correction amount Δ θ. The function F1 first executes a process P1 of determining whether the cooling water temperature T _ cw is equal to or lower than a 1 st threshold T1, which is a predetermined temperature threshold. In the process P1, if the function F1 determines that the cooling water temperature T _ cw is equal to or lower than the 1 st threshold T1 (yes), the next process P2 is executed.

The control device 10 executes the cooling water heating control for increasing the energy distribution η _ cw from the engine 1, which is an internal combustion engine, to the cooling water in the process P2. The control device 10 executes advance control for advancing the ignition time θ in the cooling water warming control, for example. More specifically, the control device 10 sets the ignition time correction amount Δ θ to a negative value by, for example, the function F1. Here, the following setting C1 and setting C2 may be selected as the setting of the ignition time correction amount Δ θ, for example.

At setting C1, for example, ignition timing correction amount Δ θ is set to a predetermined negative fixed value. Under the setting C2, the ignition time correction amount Δ θ is set, for example, in a correlated manner with the cooling water temperature deviation Δ T _ cw. Here, the cooling water temperature deviation Δ T _ cw is, for example, a difference between the cooling water temperature T _ cw and a 1 st threshold T1 which is a predetermined temperature threshold. More specifically, at the setting C2, the ignition time correction amount Δ θ can be set as in the following expression (1) or (2), for example.

Δθ＝A×(T1－T_cw)+Δθas(T_cw＜T1)···(1)

Δθ＝Δθas(T_cw≥T1)···(2)

In the above equations (1) and (2), a is a positive constant, and Δ θ as is a reference advance correction amount. In the setting C2, by setting the ignition time correction amount Δ θ as in the above (1) and (2), the ignition time correction amount Δ θ and the cooling water temperature deviation Δ T _ cw can be made to have a negative correlation. In other words, at the setting C2, the ignition time correction amount Δ θ (absolute value), which is the correction amount of the advance correction, increases as the cooling water temperature deviation Δ T _ cw increases.

In the advance correction, the ignition time correction amount Δ θ is a negative value. Therefore, increasing the ignition time correction amount Δ θ as the advance correction amount is synonymous with increasing the absolute value of the ignition time correction amount Δ θ. The reference advance correction amount Δ θ as may be determined, for example, from a map created by obtaining parameters such as the cooling water temperature T _ cw and the operating conditions through experiments or simulations performed in advance using the engine 1. The reference advance correction amount Δ θ as may be set to a negative value.

In this manner, the function F1 of the control device 10 for calculating the ignition time correction amount Δ θ executes the advance control for advancing the ignition time in the coolant heating control executed in the process P2. In the advance control executed in the process P2, when the setting C2 is selected, the function F1 increases the ignition time correction amount Δ θ, which is an advance correction amount for advancing the ignition time θ, as the difference between the 1 st threshold value T1 and the cooling water temperature T _ cw increases.

As described above, in the process P2 shown in fig. 6, the function F1 of fig. 4 for calculating the ignition time correction amount Δ θ sets the negative ignition time correction amount Δ θ in accordance with the setting C1, the setting C2, or the like, for example, and outputs the result to the function F2 for correcting the ignition time. As a result, the processing shown in fig. 6 is terminated, and the ignition timing correction function F2 in fig. 4 calculates the corrected ignition timing θ' from the ignition timing correction amount Δ θ input from the function F1 and the latest ignition timing θ.

The ignition control unit 16 shown in fig. 2 converts the corrected ignition timing θ' calculated by the function F2 of correcting the ignition timing of the control device 10 into an ignition signal S _ ign and outputs the ignition signal S _ ign to the ignition coil 1F shown in fig. 2. As a result, as shown in fig. 5, for example, the ignition timing θ of the engine 1 is advanced from the optimal ignition timing θ o, and the energy distribution η _ cw from the engine 1, which is an internal combustion engine, to the coolant is increased.

As a result, in setting C1 in which the ignition timing correction amount Δ θ is set to a predetermined negative fixed value, as shown by the dotted line in the graph of the ignition timing θ in fig. 7, for example, during the period from time t0 to time t1, the ignition timing θ is corrected to a negative fixed value, and the torque τ is decreased. As shown by the dotted line in the graph of the cooling water temperature T _ cw in fig. 7, in the setting C1 of the present embodiment, the cooling water temperature T _ cw can be increased earlier than in the comparative example shown by the solid line.

In the setting C2, the ignition time correction amount Δ θ, which is an advance correction amount, increases as the cooling water temperature deviation Δ T _ cw increases. As a result, as shown by the one-dot chain line in the graph of the ignition time θ in fig. 7, for example, during a period from time t0 to time t2, the ignition time θ gradually advances so as to approach the optimal ignition time θ o, and the ignition time correction amount Δ θ as the advance correction amount gradually decreases. As indicated by a one-dot chain line in the graph of the torque τ, the torque τ gradually increases from a value lower than the required torque τ _ req toward the required torque τ _ req. As indicated by a one-dot chain line in the graph of the cooling water temperature T _ cw, in the setting C2 of the present embodiment, the cooling water temperature T _ cw can be increased earlier than in the comparative example shown by the solid line.

The cooling water temperature T _ cw rises, for example, at time T1 exceeding the 1 st threshold T1, by the setting C1 of the advance control of the present embodiment shown by a dotted line in the graph of the cooling water temperature T _ cw in fig. 7. Further, the cooling water temperature T _ cw rises, for example, exceeding the 1 st threshold T1 at time T2, by the setting C2 of the advance control of the present embodiment shown by a one-dot chain line in the graph. Then, in the process P1 shown in fig. 6, the function F1 shown in fig. 4 for calculating the ignition time correction amount Δ θ determines that the cooling water temperature T _ cw is not equal to or less than the 1 st threshold T1 (no), and executes the next process P3.

In the process P3, the function F1 sets the ignition time correction amount Δ θ to zero, and ends the process flow shown in fig. 6. Then, the function F2 of correcting the ignition timing in fig. 4 calculates a corrected ignition timing θ' from the ignition timing correction amount Δ θ input from the function F1 and the latest ignition timing θ. In this case, the ignition timing θ' calculated by the function F2 is equal to the latest ignition timing θ without correcting the ignition timing θ.

As a result, as shown by the dotted line in the graph of the ignition time θ in fig. 7, in the setting C1 of the advance control according to the present embodiment, the ignition time correction amount Δ θ becomes zero after the time t 1. As indicated by a one-dot chain line in the graph, the ignition time correction amount Δ θ becomes zero after time t2 at setting C2 of the advance control of the present embodiment. Accordingly, the ignition time θ shown in fig. 5 does not change from the optimum ignition time θ o, for example, and the energy distributions η _ i, η _ cw, and η _ exh to the power, the coolant, and the exhaust gas of the engine 1 are substantially constant.

As a result, as shown in fig. 7, the rate of increase in the cooling water temperature T _ cw is also substantially constant. Thereafter, for example, at time t3, the engine 1 is turned off, the operation of the engine 1 is stopped, and the control of the engine 1 by the control device 10 is ended.

Fig. 8 is a flowchart illustrating the calculation process in the function F1 of calculating the ignition time correction amount Δ θ in fig. 4. Fig. 9 is a graph showing a state of the engine 1 in the processing flow of fig. 8.

The horizontal axis and the vertical axis of each graph in fig. 9 are the same as those in fig. 7 described above, except for the vertical axis of the lowermost graph. The vertical axis of the lowermost graph of fig. 9 is the catalyst temperature T _ cat. In each of the graphs other than the graphs showing the operation and the shut-off of the engine 1 in fig. 9, the states of the engine 1 in the delay control setting C3 and the delay control setting C4, which are performed by the control device 10 of the present embodiment, and the comparative form in which the conventional control device is used, are shown by a solid line, a dotted line, and an alternate long and short dash line.

As shown in fig. 9, when the required torque τ _ req is input at time t0, the engine 1 is started and operated. Here, in order to easily understand the operation of the engine 1, a case where the required torque τ _ req is fixed will be described. In a comparative mode using a conventional control device, when the engine 1 is started at time t0, the throttle opening P _ thr and the ignition timing θ are set so as to satisfy the required torque τ _ req.

Thus, in the graph of the ignition time θ and the graph of the torque target value τ in fig. 9, the ignition time θ and the torque τ are maintained substantially constant in the comparative form shown by the solid line. Further, in the operating state where the engine 1 is operating, energy is supplied from the engine 1 to the exhaust gas in the form of heat. Thus, in the graph of the catalyst temperature T _ cat of fig. 9, the catalyst temperature T _ cat gradually increases in the comparative form shown by the solid line. The catalyst temperature T _ cat can be inferred from the exhaust gas temperature T _ exh, for example, as described above.

On the other hand, in the control device 10 of the present embodiment, when the engine 1 is started at time t0, the process flow shown in fig. 8 is started by the function F1 of fig. 4 that calculates the ignition time correction amount Δ θ. The function F1 first executes a process P4 of determining whether the catalyst temperature T _ cat is equal to or lower than a 2 nd threshold T2, which is a predetermined temperature threshold. In the process P4, if the function F1 determines that the catalyst temperature T _ cat is equal to or lower than the 2 nd threshold T2 (yes), the next process P5 is executed.

The control device 10 executes a catalyst warming control for increasing the energy distribution η _ exh from the engine 1, which is an internal combustion engine, to the exhaust gas in the process P5. The control device 10 executes retard control for retarding the ignition time θ in the catalyst warming control, for example. More specifically, the control device 10 sets the ignition time correction amount Δ θ to a positive value by, for example, the function F1. Here, the following setting C3 and setting C4 may be selected as the setting of the ignition time correction amount Δ θ, for example.

At setting C3, for example, the ignition timing correction amount Δ θ is set to a predetermined positive fixed value. At setting C4, the ignition time correction amount Δ θ is set, for example, in a manner correlated with the catalyst temperature deviation Δ T _ cat. Here, the catalyst temperature deviation Δ T _ cat is, for example, a difference between the catalyst temperature T _ cat and a 2 nd threshold value T2 which is a predetermined temperature threshold value. More specifically, at setting C4, the ignition time correction amount Δ θ can be set as in the following expression (3) or (4), for example.

Δθ＝B×(T2－T_cat)+Δθds (T_cat＜T2)···(3)

Δθ＝Δθds (T_cat≥T2)···(4)

In the above expressions (3) and (4), B is a positive constant, and Δ θ ds is a reference retard correction amount. By setting the ignition time correction amount Δ θ in the setting C4 as in the above (3) and (4), the ignition time correction amount Δ θ and the catalyst temperature deviation Δ T _ cat can have a positive correlation. In other words, at the setting C2, the ignition timing correction amount Δ θ, which is the correction amount for the retard correction, increases as the catalyst temperature deviation Δ T _ cat increases.

In the retard correction, the ignition time correction amount Δ θ is a positive value. Therefore, increasing the ignition time correction amount Δ θ as the retard correction amount is synonymous with increasing the ignition time correction amount Δ θ. The reference retard correction amount Δ θ ds may be determined, for example, from a map created by obtaining parameters such as the catalyst temperature T _ cat and the operating conditions through experiments or simulations performed in advance using the engine 1. The reference retard correction amount Δ θ ds may be set to a positive value.

In this manner, the function F1 of the control device 10 for calculating the ignition time correction amount Δ θ executes the retard control for retarding the ignition time in the catalyst warming control executed in the process P5. In the retard control executed in this process P5, if the setting C4 is selected, the function F1 increases the ignition time correction amount Δ θ, which is a retard correction amount for retarding the ignition time θ, as the difference between the 2 nd threshold value T2 and the catalyst temperature T _ cat increases.

As described above, in the process P5 shown in fig. 8, the function F1 of fig. 4 for calculating the ignition time correction amount Δ θ sets the positive ignition time correction amount Δ θ in accordance with the setting such as the setting C3 or the setting C4, and outputs the result to the function F2 for correcting the ignition time. As a result, the processing shown in fig. 8 is ended, and the function F2 of correcting the ignition timing in fig. 4 calculates a corrected ignition timing θ' from the ignition timing correction amount Δ θ input from the function F1 and the latest ignition timing θ.

The ignition control unit 16 shown in fig. 2 converts the corrected ignition timing θ' calculated by the function F2 of correcting the ignition timing of the control device 10 into an ignition signal S _ ign and outputs the ignition signal S _ ign to the ignition coil 1F shown in fig. 2. As a result, as shown in fig. 5, for example, the ignition time θ of the engine 1 is retarded from the optimal ignition time θ o, and the energy distribution η _ exh from the engine 1, which is an internal combustion engine, to the exhaust gas is increased.

As a result, in setting C3 in which the ignition timing correction amount Δ θ is set to a predetermined positive fixed value, as shown by a dotted line in the graph of the ignition timing θ in fig. 9, for example, during a period from time t0 to time t1, the ignition timing θ is corrected to a positive fixed value, and the torque τ is decreased. As indicated by the dotted line in the graph of the catalyst temperature T _ catw in fig. 9, the catalyst temperature T _ cat can be increased earlier in the setting C3 of the present embodiment than in the comparative example indicated by the solid line.

In the setting C4, the ignition time correction amount Δ θ, which is a retard correction amount, is increased as the catalyst temperature deviation Δ T _ cat is increased. As a result, as shown by the one-dot chain line in the graph of the ignition time θ in fig. 9, for example, during a period from time t0 to time t2, the ignition time θ gradually advances so as to approach the optimal ignition time θ o, and the ignition time correction amount Δ θ as the retard correction amount gradually decreases. As indicated by a one-dot chain line in the graph of the torque τ, the torque τ is gradually increased from a value lower than the required torque τ _ req toward the required torque τ _ req. As indicated by the one-dot chain line in the graph of the catalyst temperature T _ cat, the catalyst temperature T _ cat can be increased earlier in the setting C4 of the present embodiment than in the comparative example indicated by the solid line.

The catalyst temperature T _ cat rises, for example, exceeds the 2 nd threshold T2 at time T1, by the setting C3 of the retard control of the present embodiment shown by the dotted line in the graph of fig. 9. Further, the catalyst temperature T _ cat rises, for example, exceeds the 2 nd threshold T2 at time T2, according to the setting C4 of the retard control of the present embodiment shown by a one-dot chain line in the graph. Then, in the processing P1 shown in fig. 8, the function F1 shown in fig. 4 for calculating the ignition timing correction amount Δ θ determines that the catalyst temperature T _ cat is not equal to or less than the 2 nd threshold value T2 (no), and executes the next processing P6.

In the process P6, the function F1 sets the ignition time correction amount Δ θ to zero, and ends the process flow shown in fig. 8. Then, the function F2 of correcting the ignition timing in fig. 4 calculates a corrected ignition timing θ' from the ignition timing correction amount Δ θ input from the function F1 and the latest ignition timing θ. In this case, the ignition timing θ' calculated by the function F2 is equal to the latest ignition timing θ without correcting the ignition timing θ.

As a result, as shown by the dotted line in the graph of the ignition time θ of fig. 9, in the setting C3 of the retard control of the present embodiment, the ignition time correction amount Δ θ becomes zero after time t 1. As indicated by a one-dot chain line in the graph, the ignition time correction amount Δ θ becomes zero after time t2 in the retard control setting C4 of the present embodiment. Accordingly, the ignition timing θ shown in fig. 5 does not change from the optimal ignition timing θ o, for example, and the energy distributions η _ i, η _ cw, and η _ exh to the power, the coolant, and the exhaust gas of the engine 1 are substantially constant.

As a result, as shown in fig. 9, the rate of increase in the catalyst temperature T _ cat is also substantially constant. Thereafter, at time t3, for example, the engine 1 is turned off, the operation of the engine 1 is stopped, and the control of the engine 1 by the control device 10 is ended.

Fig. 10 is a flowchart illustrating an example of the processing in the function F2 of correcting the ignition timing in fig. 4. As described above, the function F2 of correcting the ignition timing is inputted with the current ignition timing θ and the ignition timing correction amount Δ θ set by the function F1 of calculating the ignition timing correction amount Δ θ. When the function F2 starts the processing flow shown in fig. 10, a process P7 is first executed in which the sum of the ignition time θ and the ignition time correction amount Δ θ is set as the ignition time reference value θ _ ref.

Next, the function F2 executes a process P8 of determining whether the ignition time correction amount Δ θ is negative. In this process P8, if the function F2 determines that the ignition time correction amount Δ θ is negative (yes), a process P9 of determining whether the ignition time reference value θ _ ref is greater than the advance limit value θ _ lim (-) is performed. The advance limit value θ _ lim (-) is set as described later.

In this process P9, when the function F2 determines that the ignition time reference value θ _ ref is greater than the advance limit value θ _ lim (-) (yes), a process P10 of setting the corrected ignition time θ' to the advance limit value θ _ lim (-) is executed, and the process flow shown in fig. 10 is ended. On the other hand, in the process P9, when the function F2 determines that the ignition time reference value θ _ ref is equal to or less than the advance limit value θ _ lim (-) (no), the process P11 of setting the corrected ignition time θ' as the ignition time reference value θ _ ref is executed, and the process flow shown in fig. 10 is ended.

Further, in the aforementioned process P8, if the function F2 determines that the ignition time correction amount Δ θ is 0 or more (no), a process P12 of determining whether the ignition time reference value θ _ ref is larger than the retard limit value θ _ lim (+) is performed. In this process P12, when the function F2 determines that the ignition time reference value θ _ ref is equal to or less than the retard limit value θ _ lim (+) (no), the above-described process P11 of setting the corrected ignition time θ' as the ignition time reference value θ _ ref is executed, and the process flow shown in fig. 10 is ended.

On the other hand, in the process P12, when the function F2 determines that the ignition time reference value θ _ ref is larger than the retard limit value θ _ lim (+) (yes), a process P13 of setting the corrected ignition time θ' to the retard limit value θ _ lim (+) is executed, and the process flow shown in fig. 10 is ended.

Here, the setting of the advance limit value θ _ lim (-) described above will be described. The advance limit value θ _ lim (-) is a limit value of the ignition time θ when the ignition time θ is advanced, and is set, for example, in accordance with the ignition time θ at which abnormal combustion occurs in the engine 1.

More specifically, the ignition timing θ at which abnormal combustion occurs is mapped based on the operating conditions such as the torque τ and the rotational speed of the engine 1 and the cooling water temperature T _ cw. Then, an advance limit value θ _ lim (-) at which abnormal combustion does not occur is set based on the ignition time θ at which abnormal combustion occurs, which is derived from a map using actual operating conditions and the cooling water temperature T _ cw.

In the case where the map as described above is not used, for example, the ignition timing θ at which abnormal combustion occurs can be calculated by the function F2 of correcting the ignition timing of the control device 10 based on the relationship between the detection result of the knock sensor S7 and the ignition timing θ. In this case, the function F2 sets an advance limit value θ _ lim (-) at which abnormal combustion does not occur, based on the calculated ignition time θ at which abnormal combustion occurs.

Further, when the torque τ of the engine 1 is smaller than the friction torque for operating the engine 1, the engine 1 cannot be operated. Therefore, the advance limit value θ _ lim (-) of the advance control is set according to the range in which the rotation of the engine 1 as the internal combustion engine can be continued. That is, when the torque τ of the engine 1 is small and the difference between the torque τ of the engine and the friction torque is smaller than the predetermined value, the advance limit value θ _ lim (-) is set based on the relationship between the torque τ of the engine 1 and the friction torque.

More specifically, the friction torque is mapped according to, for example, the operating condition of the engine 1 and the cooling water temperature T _ cw. Then, the friction torque τ _ f is derived from the map using the actual operating conditions and the cooling water temperature T _ cw. Further, the advance limit value θ _ lim (-) is calculated from the following equation (5) in relation to the required torque τ _ req (indicated torque τ _ a transmitted to the crankshaft 1a at the optimum ignition time θ o due to combustion of the air-fuel mixture) under the operating conditions.

θ_lim(-)＝θ_mbt－{(τ_a－τ_f)/(C×τ_f)} ^0.5 ···(5)

In the above equation (5), θ _ mbt is an ignition time θ at which the indicated torque τ _ a of the engine 1 reaches a maximum, and C is a coefficient of a numerical expression in which an energy distribution η _ i to power of the engine 1 corresponding to the ignition time θ is approximated by a quadratic function of the ignition time θ. The approximate expression is as shown in the following formula (6).

η_i(θ)＝η_i_max+C×(θ－θ_mbt) ² ···(6)

In the above equation (6), η _ i _ max is the maximum value of the energy distribution η _ i of the engine 1 to the motive power. Note that, without using an approximate expression, the energy distribution η _ i of the engine 1 to the motive power according to the ignition time θ may be mapped and the advance limit value θ _ lim (-) may be derived using the map. As shown in fig. 11, the advance limit value θ _ lim (-) may be set from the viewpoint of energy use efficiency.

Fig. 11 is a graph illustrating the energy distribution of the engine 1 as an internal combustion engine. In the graph of fig. 11, the vertical axis represents the energy E, and the horizontal axis represents the ignition time θ of the engine 1. In the graph of fig. 11, the energy distribution η — i of the engine 1 to the motive power is indicated by a solid line. Further, the sum of the energy distribution η _ i of the engine 1 to the motive power and the energy distribution η _ cw from the engine 1 to the cooling water, i.e., the motive-cooling water distribution η _ i + η _ cw, is indicated by a dotted line. Further, the sum of the energy distribution η _ i of the engine 1 to the power and the energy distribution η _ exh from the engine 1 to the exhaust gas, i.e., the power-exhaust gas distribution η _ i + η _ exh, is indicated by a broken line.

The advance limit value θ _ lim (-) in the process P9 of fig. 10 may be set to the ignition time θ 1 at which the power-cooling water distribution η _ i + η _ cw shown in fig. 11 reaches the maximum, for example.

Next, the setting of the retardation limit value θ _ lim (+) described above will be described. The retard limit value θ _ lim (+) is a limit value of the ignition time θ when the ignition time θ is retarded, and is set, for example, in accordance with the ignition time θ at which the torque τ of the engine 1 fluctuates due to an unstable combustion state when the retard of the ignition time θ is increased in the engine 1.

More specifically, the ignition time θ at which the variation in the torque τ is larger than a predetermined threshold value is mapped, for example, in accordance with the operating conditions such as the torque τ and the rotational speed of the engine 1 and the coolant temperature T _ cw. Then, a retard limit value θ _ lim (+) at which the variation of the torque τ is equal to or smaller than a threshold value is set in accordance with the ignition time θ at which the variation of the torque τ derived from the map using the actual operating condition and the cooling water temperature T _ cw increases.

In the case where the map as described above is not used, for example, the ignition time θ at which the torque τ becomes unstable can be calculated by the function F2 of the control device 10 that corrects the ignition time based on the relationship between the ignition time θ and the variation in the rotation speed of the engine 1 based on the detection result of the crank angle sensor S1. In this case, the function F2 sets a retard limit value θ _ lim (+) at which the torque τ does not become unstable, based on the ignition time θ at which the calculated torque τ becomes unstable.

When the torque τ of the engine 1 is smaller than the friction torque for operating the engine 1, the engine 1 cannot be operated. Therefore, the retard limit value θ _ lim (+) of the retard control is set according to the range in which the rotation of the engine 1 as the internal combustion engine can be continued. That is, when the torque τ of the engine 1 is small and the difference between the torque τ of the engine and the friction torque is smaller than the predetermined value, the retard limit value θ _ lim (+) is set in accordance with the relationship between the torque τ of the engine 1 and the friction torque.

More specifically, for example, like the advance limit value θ _ lim (-) described above, the retard limit value θ _ lim (+) is calculated from the following equation (7) in relation to the required torque τ _ req (indicated torque τ _ a at the optimal ignition time θ o) under the actual operating conditions.

θ_lim(+)＝θ_mbt－{(τ_a－τ_f)/(C×τ_f)} ^0.5 ···(7)

In addition, as with the advance limit value θ _ lim (-) described above, the retard limit value θ _ lim (+) may be derived by mapping the energy distribution η _ i of the engine 1 to the motive power according to the ignition time θ without using the approximate expression of the expression (6).

Next, an operation of the control device 10 for an internal combustion engine according to the present embodiment will be described.

The regulations on fuel consumption and emissions of vehicles such as automobiles are expected to be further strengthened in the future. In particular, regulations relating to fuel consumption have been receiving increased attention in recent years due to problems such as an increase in fuel price, an influence on global warming, and energy depletion. In order to meet the regulations on fuel consumption of automobiles, which have been intensified year by year, the market of hybrid automobiles having a good fuel consumption reduction effect has been expanding.

A hybrid vehicle includes a motor and an engine as power sources, and drives both the motor and the engine or one of the motor and the engine according to a running condition, thereby efficiently running the vehicle. In addition, the hybrid vehicle uses the motor as a generator during deceleration to convert the kinetic energy of the vehicle into electric energy and store the electric energy in the storage device, and drives the motor using the electric energy to run the vehicle, thereby improving fuel efficiency.

An engine of a series hybrid vehicle is frequently stopped as compared with a normal vehicle or a parallel hybrid vehicle, for example. More specifically, the engine of the series hybrid vehicle is operated under a limited condition, for example, during charging of the power storage device or during power generation when the output of the power storage device is insufficient, thereby improving fuel efficiency. However, the reduction in the operating time of the engine reduces the energy distribution from the engine to the exhaust gas and the energy distribution from the engine to the coolant, and thus the reduction in the catalyst temperature and the reduction in the coolant temperature of the exhaust system are more likely to occur compared to an automobile driven by the engine.

The conventional exhaust heat control device described in patent document 1 achieves a certain effect when exhaust heat recovery of the engine by the coolant is mainly performed. However, the conventional exhaust heat control device has a problem that it cannot cope with a situation in which the operation frequency of the engine is low and both the temperature of the catalyst and the temperature of the coolant included in the exhaust system of the engine are lowered.

In contrast, the control device 10 for an internal combustion engine according to the present embodiment acquires the cooling water temperature T _ cw and the catalyst temperature T _ cat of the exhaust system as described above, and controls the ignition timing θ of the engine 1 as the internal combustion engine. As described above, the control device 10 executes the cooling water warming control in the process P2 shown in fig. 6, and executes the catalyst warming control in the process P5 shown in fig. 8. As shown in fig. 6, the coolant heating control is a control for increasing the energy distribution η _ cw from the internal combustion engine to the coolant when the coolant temperature T _ cw is equal to or lower than the 1 st threshold T1. As shown in fig. 8, the catalyst warming control is a control for increasing the energy distribution from the internal combustion engine to the exhaust gas when the catalyst temperature T _ cat is equal to or lower than the 2 nd threshold value T2.

With such a configuration, the control device 10 for an internal combustion engine according to the present embodiment can efficiently increase the catalyst temperature T _ cat and the cooling water temperature T _ cw, respectively, compared to the conventional exhaust heat control device. More specifically, the energy distribution η _ i to power, the energy distribution η _ exh to exhaust gas, and the energy distribution η _ cw to cooling water of the engine 1 shown in fig. 5 can be operated by correcting the ignition time θ according to the catalyst temperature T _ cat and the cooling water temperature T _ cw, which are important parameters of the internal combustion engine. Accordingly, appropriate control according to the state of the internal combustion engine, the cooling water temperature T _ cw, and the catalyst temperature T _ cat can be performed so that the cooling water temperature T _ cw and the catalyst temperature T _ cat are efficiently increased, thereby achieving an increase in heating output, a reduction in friction loss, an improvement in exhaust gas purification capability, and the like in the vehicle.

The control device 10 of the internal combustion engine according to the present embodiment executes the advance control for advancing the ignition time θ in the coolant warming control executed in the process P2 described above. Further, the control device 10 executes retard control for retarding the ignition time θ in the catalyst warming control executed in the aforementioned process P5.

With such a configuration, in the coolant heating control, as shown in fig. 5, the ignition time θ is advanced to increase the energy distribution η _ cw from the engine 1 to the coolant, and as shown in fig. 7, the coolant temperature T _ cw can be efficiently increased. In the catalyst warming control, as shown in fig. 5, the ignition time θ is retarded to increase the energy distribution η _ exh from the engine 1 to the exhaust gas, and as shown in fig. 9, the catalyst temperature T _ cat can be efficiently increased.

In addition, when the setting C2 is selected in the advance control executed in the process P2 described above, the control device 10 for the internal combustion engine according to the present embodiment increases the cooling water temperature deviation Δ T _ cw, which is the difference between the 1 st threshold value T1 and the cooling water temperature T _ cw, as the ignition time correction amount Δ θ is increased. With this configuration, as shown in fig. 7, the ignition time correction amount Δ θ as the advance correction amount is large near the time T0 at which the cooling water temperature deviation Δ T _ cw is large, and when the cooling water temperature deviation Δ T _ cw decreases with the elapse of time, the ignition time correction amount Δ θ as the advance correction amount decreases. As a result, as shown by the one-dot chain line in the graph of the torque τ in fig. 7, the change in the torque τ can be made gentle, and the load on the system can be reduced.

Further, when the setting of C4 is selected in the retard control executed in the process P5 described above, the control device 10 for the internal combustion engine according to the present embodiment increases the ignition time correction amount Δ θ, which is a retard correction amount for retarding the ignition time θ, as the catalyst temperature deviation Δ T _ cat, which is the difference between the 2 nd threshold value T2 and the catalyst temperature T _ cat, increases. With this configuration, as shown in fig. 9, the ignition time correction amount Δ θ as the retard correction amount is large near time T0 at which the cooling water temperature deviation Δ T _ cw is large, and when the cooling water temperature deviation Δ T _ cw decreases with the elapse of time, the ignition time correction amount Δ θ as the retard correction amount decreases. As a result, as shown by a one-dot chain line in the graph of the torque τ of fig. 9, the change in the torque τ can be made gentle, and the load on the system can be reduced.

In the advance control described above, the control device 10 for the internal combustion engine according to the present embodiment executes a process P10 for setting the ignition time correction amount Δ θ as the advance correction amount to the advance limit value θ _ lim (-) when the ignition time correction amount Δ θ as the advance correction amount exceeds the advance limit value θ _ lim (-) as shown in fig. 10. With such a configuration, it is possible to avoid setting of the ignition time θ beyond the advance limit value θ _ lim (-) that changes depending on the operating state of the engine 1, the cooling water temperature T _ cw, and the like. As a result, the energy of the engine 1 can be efficiently distributed according to the cooling water temperature T _ cw and the catalyst temperature T _ cat while suppressing damage, unexpected stop, variation in the torque τ, and the like of the engine 1.

In the retard control described above, the control device 10 for the internal combustion engine according to the present embodiment executes a process P13 in which the ignition time correction amount Δ θ as the retard correction amount is set to the retard limit value θ _ lim (+) when the ignition time correction amount Δ θ as the retard correction amount exceeds the retard limit value θ _ lim (+) as shown in fig. 10. With such a configuration, it is possible to avoid setting of the ignition time θ exceeding the retard limit value θ _ lim (+) that changes depending on the operating state of the engine 1, the cooling water temperature T _ cw, and the like. As a result, the energy of the engine 1 can be efficiently distributed according to the cooling water temperature T _ cw and the catalyst temperature T _ cat while suppressing damage, unexpected stop, variation in the torque τ, and the like of the engine 1.

In the control device 10 for an internal combustion engine according to the present embodiment, the advance limit value θ _ lim (-) is set based on one of the ignition time θ at which abnormal combustion occurs in the engine 1 as the internal combustion engine and the ignition time at which the power-cooling water distribution η _ i + η _ cw reaches the maximum. The power-cooling water distribution η _ i + η _ cw is the sum of the energy distribution η _ i of the engine 1 to the power, i.e., the drive system and the energy distribution η _ cw to the cooling water. With this configuration, in the cooling water warming control for raising the temperature of the cooling water, the energy for the power of the engine 1 and the energy for raising the temperature of the cooling water can be maximized, and the energy utilization efficiency of the entire system can be improved.

In the control device 10 for an internal combustion engine according to the present embodiment, the retard limit value θ _ lim (+) described above is set in accordance with the ignition timing at which the combustion state of the engine 1 as the internal combustion engine becomes unstable. With such a configuration, in the catalyst warming control for raising the temperature of the catalyst temperature T _ cat, the combustion state of the engine 1 can be stabilized, the torque τ can be prevented from varying, and the torque τ can be stabilized.

In the control device 10 for an internal combustion engine according to the present embodiment, the advance limit value θ _ lim (-) and the retard limit value θ _ lim (+) for the advance control described above are set in accordance with a range in which the rotation of the engine 1 as the internal combustion engine can be continued. With this configuration, the torque τ of the engine 1 can be prevented from being smaller than the friction torque, and the engine 1 can be reliably driven.

As described above, according to the present embodiment, it is possible to provide the control device 10 for the internal combustion engine capable of efficiently increasing the catalyst temperature T _ cat and the cooling water temperature T _ cw, respectively, as compared with the conventional exhaust heat control device.

[ embodiment 2]

Next, embodiment 2 of the control device for an internal combustion engine according to the present invention will be described with reference to fig. 1 to 3 and fig. 12 to 15.

Fig. 12 is a functional block diagram of the control device 10 of the present embodiment. The control device 10 for an internal combustion engine according to the present embodiment has a function F1 of calculating the ignition time correction amount Δ θ and a function F2 of correcting the ignition time θ, for example, as in the control device 10 for an internal combustion engine according to embodiment 1 described above. The control device 10 of the present embodiment further has a function F3 of correcting the torque τ. In the control device 10 of the present embodiment, the same components as those of the control device 10 of embodiment 1 described above are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 12, the function F3 for correcting the torque τ takes as input, for example, the required torque τ _ req and the rotation speed R _ eng of the engine 1, the ignition time θ before the correction, the ignition time θ' after the correction, and the throttle opening P _ thr. Function F3 calculates, based on these inputs, a corrected throttle opening P _ thr 'for correcting the decrease in torque τ at the corrected ignition time θ'.

Fig. 13 is a flowchart illustrating the processing performed by the torque τ correcting function F3 in fig. 12. When the function F3 starts the process flow shown in fig. 13, first, a process P21 is executed to calculate the torque τ _0 of the engine 1 at the ignition time θ before correction. In the process P21, the function F3 can calculate the torque τ _0 of the engine 1 at the ignition time θ before correction by the following equation (8) using the energy distributions η _ i, η _ exh, and η _ cw to the power, the exhaust gas, and the cooling water of the engine 1 as shown in fig. 5, for example.

τ_0＝η_i(θ0)×Mf×Hl/(2×π×R)···(8)

Here, η _ i (θ 0) is an energy distribution η _ i of the engine 1 to the motive power at the ignition time θ 0. Further, Mf is a fuel supply amount [ kg ] per one cycle of the engine 1, Hl is a lower heating value [ J/kg ] of the fuel, pi is a circumferential ratio, and R is a crank radius [ m ]. The torque τ _0 of the engine 1 at the ignition time θ before correction calculated as described above is considered to be equal to the required torque τ _ req.

Next, the function F3 of correcting the torque τ executes a process P22 of calculating the torque τ _ m at the corrected ignition time θ' by the following equation (9). Here, η _ i (θ m) is an energy distribution η _ i of the engine 1 to the motive power at the ignition time θ m.

τ_m＝η_i(θm)×Mf×Hl/(2×π×R)···(9)

Next, the function F3 of correcting the torque τ executes a process P23 of subtracting the torque τ _ m at the corrected ignition time θ' calculated in the process P22 from the torque τ _0 of the engine 1 at the pre-correction ignition time θ calculated in the process P21 to calculate a torque reduction amount Δ τ.

Next, the function F3 of correcting the torque τ executes a process P24 of calculating a correction amount Δ P _ thr of the throttle opening. The correction amount Δ P _ thr of the throttle opening is a correction amount of the throttle opening P _ thr for compensating the amount of decrease in the torque τ at the ignition time θ' after the correction to generate the torque τ at the ignition time θ before the correction.

Further, the control device 10 stores, for example, in the ROM14, a map indicating a relationship between the throttle opening P _ thr of the electronically controlled throttle valve 1c and the flow rate FR _ air of the air. The function F3 for correcting the torque τ obtains the current flow rate FR _ air from the current throttle opening P _ thr using the map. Further, the function F3 obtains a corrected air flow rate FR _ air' shown in the following equation (10) using the air flow rate FR _ air before correction, the torque reduction amount Δ τ after correction, and the torque τ _0 before correction.

FR_air'＝FR_air×(1+Δτ/τ_0)···(10)

Then, the function F3 calculates a correction amount Δ P _ thr of the throttle opening to realize the corrected air flow rate FR _ air' based on the current throttle opening P _ thr. Next, the function F3 of correcting the torque τ executes a process P25 of adding the correction amount Δ P _ thr of the calculated throttle opening to the current throttle opening P _ thr to obtain a corrected throttle opening P _ thr 'for realizing the corrected air flow rate FR _ air'. By the above operation, the processing flow shown in fig. 13 is ended. The flow rate of air taken into the engine 1 may be increased by a device other than the electronically controlled throttle 1 c.

Fig. 14 is a graph showing the result of the processing of fig. 13. Fig. 14 shows a graph having the same vertical axis as the graph shown in fig. 7 described in embodiment 1 above, except that a graph having the throttle opening degree P _ thr on the vertical axis is added.

In each of the graphs other than the graph showing the operation and the shutdown of the engine 1 in fig. 14, the states of the engine 1 are shown by the alternate long and short dash line and the solid line, respectively, of the advance control setting C2 performed by the control device 10 of embodiment 1 and the advance control setting C2 performed by the control device 10 of the present embodiment described above. The setting C2 is control for increasing the advance correction amount for advancing the ignition time θ as the difference between the cooling water temperature T _ cw and the 1 st threshold value T1 increases in the advance control.

As shown in fig. 14, when the required torque τ _ req is input at time t0, the engine 1 is started and operated. Here, in order to easily understand the operation of the engine 1, a case where the required torque τ _ req is fixed will be described. In the control device 10 of embodiment 1 shown by the one-dot chain line, at time t0, when the engine 1 is started, for example, the ignition time θ before correction is set, and the throttle opening P _ thr is set so as to satisfy the required torque τ _ req.

Thus, in the setting C2 of the advance control by the control device 10 of embodiment 1, energy is supplied as heat from the engine 1 to the coolant in the operating state in which the engine 1 is operating. Thus, as shown by a one-dot chain line in the graph of the cooling water temperature T _ cw in fig. 14, the cooling water temperature T _ cw gradually increases.

On the other hand, in the setting C2 of the advance control performed by the control device 10 of the present embodiment, the respective processes shown in fig. 13 are executed, and at the time t0, the throttle opening P _ thr is corrected so as to compensate for the torque reduction amount Δ τ. That is, the control device 10 of the present embodiment increases the throttle opening P _ thr of the engine 1 as compared with the advance control performed by the control device 10 of embodiment 1 so as to compensate for the torque τ of the engine 1, which is the internal combustion engine, that decreases due to the advance control.

As a result, as shown in the graph of the torque τ, the decrease of the torque τ with respect to the required torque τ _ req, which occurs at the setting C2 of the advance control by the control device 10 of the present embodiment, and at the setting C2 of the advance control by the control device 10 of embodiment 1, is prevented. Therefore, in setting C2 of the advance control performed by the control device 10 of the present embodiment, a torque equivalent to the required torque τ _ req can be generated.

In the advance control setting C2 performed by the control device 10 according to the present embodiment, the throttle opening degree P _ thr is increased in a period from time T0 to time T1 when the cooling water temperature T _ cw is equal to or lower than the 1 st threshold value T1, compared to the advance control setting C2 performed by the control device 10 according to embodiment 1. As a result, in the setting C2 of the advanced control by the control device 10 of the present embodiment, the flow rate of the air taken into the engine 1 is increased and the energy distribution η _ cw from the engine 1 to the coolant can be increased as compared with the setting C2 of the advanced control by the control device 10 of embodiment 1.

Therefore, the controller 10 of the present embodiment can raise the cooling water temperature T _ cw in a shorter time than the controller 10 of embodiment 1 so that the final cooling water temperature T _ cw becomes higher. Further, the engine 1 can generate the required torque τ _ req during execution of the cooling water warming control. Therefore, the energy distribution η _ cw to the cooling water can be increased while the required torque τ _ req is satisfied, and the system performance using the energy of the cooling water such as heating can be improved at the same time.

The conditions to satisfy the required torque τ _ req include, for example, an idling condition in which the torque τ equivalent to the friction torque is continuously generated, and a high-speed/high-output operating condition in which the output of the power storage device 4 is insufficient and the motor 5 is driven by the output of the generator 2.

Fig. 15 is a graph showing the result of the processing of fig. 13. Fig. 15 shows a graph having the same vertical axis as the graph shown in fig. 9 described in embodiment 1 above, except that a graph having the throttle opening degree P _ thr on the vertical axis is added.

In each of the graphs other than the graph showing the operation and the shutdown of the engine 1 in fig. 15, the states of the engine 1 in the delay control setting C4 performed by the control device 10 of embodiment 1 and the delay control setting C4 performed by the control device 10 of the present embodiment described above are shown by a single-dot chain line and a solid line. The setting C4 is control for increasing the retard correction amount for retarding the ignition time θ as the difference between the catalyst temperature T _ cat and the 2 nd threshold T2 increases during the retard control.

As shown in fig. 15, when the required torque τ _ req is input at time t0, the engine 1 is started and operated. Here, in order to easily understand the operation of the engine 1, a case where the required torque τ _ req is fixed will be described. In the control device 10 of embodiment 1 shown by the one-dot chain line, at time t0, when the engine 1 is started, for example, the ignition time θ before correction is set, and the throttle opening P _ thr is set so as to satisfy the required torque τ _ req.

Thus, in the setting C4 of the delay control performed by the control device 10 of embodiment 1, energy is supplied as heat from the engine 1 to the exhaust gas in the operating state in which the engine 1 is operating.

Thus, as shown by the one-dot chain line in the graph of the catalyst temperature T _ cat in fig. 15, the catalyst temperature T _ cat gradually increases.

On the other hand, in the setting C4 of the retard control performed by the control device 10 of the present embodiment, the respective processes shown in fig. 13 are executed, and at the time t0, the throttle opening P _ thr is corrected so as to compensate for the torque reduction amount Δ τ. That is, the control device 10 of the present embodiment increases the throttle opening P _ thr of the engine 1 as compared with the retard control performed by the control device 10 of embodiment 1 so as to compensate for the torque τ of the engine 1, which is the internal combustion engine, that decreases due to the retard control.

As a result, as shown in the graph of the torque τ, the decrease in the torque τ with respect to the required torque τ _ req that occurs in the setting C4 of the delay control performed by the control device 10 of embodiment 1 is prevented in the setting C4 of the delay control performed by the control device 10 of the present embodiment. Therefore, in the setting C4 of the delay control performed by the control device 10 of the present embodiment, a torque equivalent to the required torque τ _ req can be generated.

That is, the control device 10 of the present embodiment increases the throttle opening P _ thr of the internal combustion engine so as to compensate for the torque τ of the internal combustion engine that decreases due to the advance control or the retard control. With this configuration, it is possible to prevent a decrease in the torque τ of the engine 1 during the advance control or the retard control performed by the control device 10, and to generate a torque equivalent to the required torque τ _ req.

In the delay control setting C4 performed by the control device 10 according to the present embodiment, the throttle opening degree P _ thr is increased in the period from the time T0 when the catalyst temperature T _ cat is equal to or lower than the 2 nd threshold value T2 to the time T1, as compared to the delay control setting C4 performed by the control device 10 according to embodiment 1. As a result, in the setting C4 of the retard control performed by the control device 10 of the present embodiment, the flow rate of the air taken into the engine 1 is increased and the energy distribution η _ exh from the engine 1 to the exhaust gas can be increased, compared to the setting C4 of the retard control performed by the control device 10 of embodiment 1.

Therefore, the control device 10 of the present embodiment can raise the catalyst temperature T _ cat in a shorter time than the control device 10 of embodiment 1 so that the final catalyst temperature T _ cat becomes higher. Further, the engine 1 can generate the required torque τ _ req during execution of the catalyst warming control. Therefore, the energy distribution η _ exh to the exhaust gas can be increased while the required torque τ _ req is satisfied, and the system performance and the exhaust gas purification performance by the catalyst of the exhaust system such as the three-way catalyst 1h can be improved at the same time.

[ embodiment 3]

Next, embodiment 3 of the control device for an internal combustion engine according to the present invention will be described with reference to fig. 1 to 3 and fig. 16 to 19.

Fig. 16 is a functional block diagram showing embodiment 3 of the control device for an internal combustion engine according to the present disclosure. The control device 10 of the present embodiment is different from the control device 10 of embodiment 2 described above shown in fig. 12 in that it has a function F0 of calculating the distribution of the ignition correction amount. In the control device 10 of the present embodiment, the same components as those of the control device 10 of embodiment 2 described above are denoted by the same reference numerals, and description thereof is omitted.

As shown in fig. 16, the function F0 for calculating the distribution of the ignition correction amount is inputted with, for example, the required torque τ _ req and the rotational speed R _ eng of the engine 1, the cooling water temperature T _ cw, the catalyst temperature T _ cat, and the ignition time θ. Function F0 determines the distribution of the ignition correction amount based on these inputs and outputs flag F indicating the control mode. In the control device 10 of the present embodiment, the function F1 for calculating the ignition time correction amount Δ θ is inputted with the flag F, the cooling water temperature T _ cw, and the ignition time θ outputted from the function F0.

Fig. 17 is a flowchart showing the processing in function F0 of calculating the distribution of ignition correction in fig. 16. When the function F0 starts the process flow shown in fig. 17, first, a process P31 of determining whether the catalyst temperature T _ cat is equal to or lower than the 3 rd threshold T3, which is a predetermined temperature threshold, is executed. The 3 rd threshold T3 is set to a value lower than the 2 nd threshold T2 used in the processing P33 described later, for example. In the process P31, if the function F0 determines that the catalyst temperature T _ cat is equal to or lower than the 3 rd threshold T3 (yes), the next process P32 is executed.

In the process P32, the function F0 of calculating the distribution of ignition corrections sets the flag F to "mode M1", and ends the process shown in fig. 17. The mode M1 is a mode in which the warming-up of the three-way catalyst 1h, which is a catalyst of the exhaust system of the engine 1, is prioritized.

On the other hand, in the process P31, if the function F0 of calculating the distribution of the ignition correction determines that the catalyst temperature T _ cat is higher than the 3 rd threshold T3 (no), the next process P33 is executed. In the process P33, the function F0 determines whether the catalyst temperature T _ cat is equal to or less than the 2 nd threshold T2, which is a predetermined temperature threshold. As previously described, the 2 nd threshold T2 is set to a higher temperature than the 3 rd threshold T3. In this process P33, if the function F0 determines that the catalyst temperature T _ cat is equal to or less than the 2 nd threshold T2 (yes), the next process P34 is executed.

In the process P34, the function F0 of calculating the distribution of the ignition correction determines whether or not the coolant temperature T _ cw is equal to or lower than the 1 st threshold T1. In the processing P34, when the function F0 determines that the cooling water temperature T _ cw is higher than the 1 st threshold value T1 (no), the processing P32 described above is executed, the flag F is set to the mode M1 that gives priority to warming of the three-way catalyst 1h, and the processing flow shown in fig. 17 is ended. On the other hand, in the process P34, if the function F0 determines that the cooling water temperature T _ cw is equal to or lower than the 1 st threshold T1 (yes), the next process P35 is executed.

In the process P35, the function F0 of calculating the distribution of ignition corrections sets the flag F to "mode M2", and ends the process shown in fig. 17. The mode M2 is a mode in which warming of the three-way catalyst 1h, which is a catalyst of the exhaust system of the engine 1, and warming of the cooling water are simultaneously performed.

On the other hand, in the process P33, if the function F0 of calculating the distribution of the ignition correction determines that the catalyst temperature T _ cat is higher than the 2 nd threshold T2 (no), the next process P36 is executed. In the process P36, the function F0 determines whether the cooling water temperature T _ cw is the 1 st threshold T1 or less, as in the process P34 described above. In the process P36, if the function F0 determines that the cooling water temperature T _ cw is equal to or lower than the 1 st threshold T1 (yes), the next process P37 is executed.

In the process P37, the function F0 of calculating the assignment of ignition corrections sets the flag F to the "mode M3", and ends the process shown in fig. 17. The mode M3 is a mode in which warming of the cooling water is prioritized. On the other hand, in the process P36, if the function F0 determines that the cooling water temperature T _ cw is higher than the 1 st threshold T1 (no), the next process P38 is executed.

In the process P38, the function F0 of calculating the distribution of ignition corrections sets the flag F to "mode M4", and ends the process shown in fig. 17. The mode M4 is a mode for maintaining two temperatures, the catalyst temperature T _ cat and the cooling water temperature T _ cw. Next, a flow of processing in function F1 for calculating the ignition time correction amount Δ θ in control device 10 of the present embodiment shown in fig. 16 will be described.

Fig. 18 is a flowchart showing an example of processing in the function F1 for calculating the ignition time correction amount Δ θ in fig. 16. As described above, the function F1 takes as input the flag F, the cooling water temperature T _ cw, the catalyst temperature T _ cat, and the ignition timing θ, which are output from the function F0 of calculating the distribution of the ignition correction.

When the function F1 starts the process flow shown in fig. 18, a process P41 of determining whether the flag F is the mode M1 that takes priority to warming of the catalyst is first executed.

In the process P41, if the function F1 that calculates the ignition timing correction amount Δ θ determines that the flag F is the mode M1 that gives priority to the warming of the catalyst (yes), the next process P42 is executed.

In the process P42, the function F1 executes the catalyst warming control for increasing the energy distribution η _ exh from the engine 1 to the exhaust gas, as in the process P5 in the function F1 of embodiment 1 described above.

More specifically, in the process P42, the function F1 executes retard control for setting the ignition time correction amount Δ θ to a positive value, and ends the process flow shown in fig. 18.

On the other hand, in the process P41, when the function F1 of calculating the ignition time correction amount Δ θ determines that the flag F is not the mode M1 that gives priority to warming of the catalyst (no), the next process P43 is executed. In the process P43, the function F1 determines whether the flag F is the mode M2 in which warming of the catalyst and warming of the cooling water are performed simultaneously. In this process P43, if the function F1 determines that the flag F is the mode M2 in which warming of the catalyst and warming of the cooling water are performed simultaneously (yes), the next process P44 to process P46 are executed.

In the processes P44 to P46, the function F1 of calculating the ignition time correction amount Δ θ selects the ignition time correction amounts Δ θ a and Δ θ b so that the retard control is performed on some of the cylinders 1d and the advance control is performed on the other cylinders 1d of the plurality of cylinders 1d constituting the engine 1 as the internal combustion engine.

More specifically, in the process P44, the function F1 of calculating the ignition time correction amount Δ θ calculates a positive ignition time correction amount Δ θ a as a retard correction amount for #2 and #4 cylinders 1d among the plurality of cylinders 1d constituting the engine 1 shown in fig. 2, for example. In the processing P45, the function F1 calculates a negative ignition timing correction amount Δ θ b as an advance correction amount for the #1 and #3 cylinders 1d among the plurality of cylinders 1d constituting the engine 1 shown in fig. 2, for example.

The cylinder 1d for which the advance control or the retard control is performed is not limited to the above combination.

The ignition timing correction amount Δ θ a as a retard correction amount and the ignition timing correction amount Δ θ b as an advance correction amount are calculated in the same manner as in

embodiments

1 and 2 described above.

In the process P46, the function F1 for calculating the ignition time correction amount Δ θ selects the ignition time correction amounts Δ θ a and Δ θ b based on, for example, the torque reduction amount Δ τ a by the retard control and the torque reduction amount Δ τ b by the advance control. The torque reduction amount Δ τ a by the retard control and the torque reduction amount Δ τ b by the advance control can be calculated, for example, from the following equations (11) and (12).

Δτa＝{η_i(θ)－η_i(θ+Δθa)}×Mf×Hl/(2×π×R)···(11)

Δτb＝{η_i(θ)－η_i(θ+Δθb)}×Mf×Hl/(2×π×R)···(12)

Here, Δ τ a is a torque reduction amount by retard control, Δ τ b is a torque reduction amount by advance control, and η _ i (θ) is an energy distribution η _ i of the engine 1 to the motive power at the ignition time θ.

Further, Mf is a fuel supply amount [ kg ] per cycle of the engine 1, Hl is a calorific value [ J/kg ] of the fuel, π is a circumferential ratio, and R is a crank radius [ m ].

In the process P46, the function F1 of calculating the ignition time correction amount Δ θ selects the ignition time correction amount Δ θ b calculated in the process P45 described above as the ignition time correction amount Δ θ for the advance control, for example, when the torque reduction amount Δ τ a for the retard control is larger than the torque reduction amount Δ τ b for the advance control. In this case, the function F1 calculates, as the ignition time correction amount Δ θ for the retard control, the ignition time correction amount Δ θ a by which the torque reduction amount Δ τ a for the retard control becomes equal to the torque reduction amount Δ τ b for the advance control, for example, by the following expression (13).

Δθa＝θ_mbt－θ+{2×π×R×Δτa/(C×Mf×Hl)+(θ－θ_mbt) ² } ^0.5 ···(13)

In the above equation (13), θ _ mbt is an ignition time θ at which the indicated torque τ _ a of the engine 1 reaches the maximum, π is a circumferential rate, R is a crank radius [ m ], Mf is a fuel supply amount [ kg ] per one cycle of the engine 1, and Hl is a lower heating value [ J/kg ] of the fuel. C is a coefficient of a numerical expression in which the energy distribution η _ i to the motive power of the engine 1 corresponding to the ignition time θ is approximated by a quadratic function of the ignition time θ. The approximate expression is the above expression (6). In addition, without using an approximate expression, it is possible to map the energy distribution η _ i of the engine 1 to the motive power according to the ignition time θ and use the map to derive the ignition time correction amount Δ θ a by which the torque reduction amount Δ τ a of the retard control becomes equal to the torque reduction amount Δ τ b of the advance control.

In the processing P46, the function F1 for calculating the ignition time correction amount Δ θ selects the ignition time correction amount Δ θ a calculated in the processing P44 described above as the ignition time correction amount Δ θ for the retard control, for example, when the torque reduction amount Δ τ b for the advance control is larger than the torque reduction amount Δ τ a for the retard control. In this case, the function F1 calculates, as the ignition time correction amount Δ θ for the advance control, an ignition time correction amount Δ θ b in which the torque reduction amount Δ τ b for the advance control becomes equal to the torque reduction amount Δ τ a for the retard control, for example, by the following equation (14).

Δθb＝θ_mbt－θ+{2×π×R×Δτb/(C×Mf×Hl)+(θ－θ_mbt) ² } ^0.5 ···(14)

In the above formula (14), θ _ mbt, π, R, Mf, Hl, etc. are the same as those in the above formula (13). Further, without using the approximation formula, the energy distribution η _ i of the engine 1 to the motive power according to the ignition timing θ may be mapped to derive the ignition timing correction amount Δ θ b by which the torque reduction amount Δ τ b of the advance control becomes equal to the torque reduction amount Δ τ a of the retard control using the map.

As described above, the function F1 for calculating the ignition time correction amount Δ θ selects the ignition time correction amounts Δ θ a and Δ θ b by performing the retard control in some of the cylinders 1d and the advance control in the other cylinders 1d of the engine 1 through the processes P44 to P46. Thereafter, the function F1 ends the processing flow shown in fig. 18.

On the other hand, in the process P43 described above, if the function F1 of calculating the ignition time correction amount Δ θ determines that the flag F is not the mode M2 in which the heating of the catalyst and the heating of the cooling water are performed simultaneously (no), the next process P47 is executed. In processing P47, the function F1 determines whether or not the flag F is the mode M3 that gives priority to warming of the cooling water.

In the process P47, when the function F1 for calculating the ignition time correction amount Δ θ determines that the flag F is the mode M3 in which the heating of the cooling water is prioritized (yes), the next process P48 is executed. In the process P48, the function F1 executes the cooling water warming control that increases the energy distribution η _ cw from the engine 1 to the cooling water, as in the process P2 in the function F1 of embodiment 1 described above. More specifically, in the process P48, the function F1 executes an advance control for setting the ignition time correction amount Δ θ to a negative value, and ends the process flow shown in fig. 18.

On the other hand, in the process P47, when the function F1 of calculating the ignition time correction amount Δ θ determines that the flag F is not in the mode M3 in which the heating of the cooling water is prioritized (no), the next process P49 is executed. In the process P49, the function F1 sets the ignition time correction amount Δ θ to zero and ends the process flow shown in fig. 18, as in the process P3 in the function F1 of embodiment 1 described above.

Fig. 19 is a graph showing the results of the processing shown in fig. 17 and 18. Fig. 19 is a graph having the same vertical axis as the graphs shown in fig. 14 and 15 described in embodiment 2 above, except that a graph having a vertical axis denoted by a symbol F is added.

In each of the graphs other than the graph showing the operation and shutdown of the engine 1 and the graph showing the reference symbol F in fig. 19, the state of the engine 1 under the control of the control device 10 of the present embodiment and the comparative mode using the conventional control device is shown by a solid line and a broken line, respectively. In the graph of the ignition timing θ shown in fig. 19, the ignition timing θ of the #1 and #3 cylinders 1d of the plurality of cylinders 1d of the engine 1 controlled by the control device 10 according to the present embodiment is indicated by a dotted line, and the ignition timing θ of the #2 and #4 cylinders 1d is indicated by a one-dot chain line.

As shown in fig. 19, when the required torque τ _ req is input at time t0, the engine 1 is started and operated. Here, in order to easily understand the operation of the engine 1, a case where the required torque τ _ req is fixed will be described.

The control device of the comparative form performs retard control for retarding the ignition time θ from the optimum ignition time θ o at the time of starting the engine 1, and sets the throttle opening P _ thr so as to satisfy the required torque τ _ req. By the control of the control device of this comparative embodiment, energy is supplied to the three-way catalyst 1h, which is a catalyst of the exhaust system, during the operation of the engine 1, and the catalyst temperature T _ cat increases. When the catalyst temperature T _ cat exceeds the predetermined threshold value at time T2, the control device of the comparison mode stops the retard control and returns the ignition time θ to the optimum ignition time θ o.

On the other hand, in the engine 1 under the control of the control device 10 of the present embodiment, the catalyst temperature T _ cat is equal to or lower than the 3 rd threshold T3 between the time T0 and the time T1. Therefore, the control device 10 executes a process P32 shown in fig. 17 by a function F0 of distributing the ignition correction amount, and sets the flag F to a mode M1 that gives priority to warming up the three-way catalyst 1 h. Thus, the control device 10 of the present embodiment executes the process P42 shown in fig. 18 by the function F1 of calculating the ignition time correction amount Δ θ, and calculates the positive ignition time correction amount Δ θ as the retard control amount.

As a result, as shown in fig. 19, retard control for retarding the ignition time θ is performed in all the cylinders 1d of the engine 1 between the time t0 and the time t 1. Thereby, the temperature of the catalyst temperature T _ cat rapidly rises. As the catalyst temperature deviation Δ T _ cat, which is the difference between the catalyst temperature T _ cat and the 3 rd threshold value T3, decreases, the ignition time correction amount Δ θ, which is a retard correction amount, decreases, and the ignition time θ gradually advances.

In the engine 1 under the control of the controller 10 of the present embodiment, as shown by the broken line in fig. 19, the catalyst temperature T _ cat exceeds the 3 rd threshold value T3 and is equal to or lower than the 2 nd threshold value T2, and the cooling water temperature T _ cw is equal to or lower than the 1 st threshold value T1 during the period from the time T1 to the time T2. Therefore, the function F0 of the control device 10 for distributing the ignition correction amount executes the process P35 shown in fig. 17 from the time t1 to the time t2, and sets the flag F to the mode M2 in which the three-way catalyst 1h of the engine 1 is warmed and the coolant is warmed at the same time.

Thus, the control device 10 of the present embodiment executes the processes P44 to P46 shown in fig. 18 by the function F1 of calculating the ignition time correction amount Δ θ. Thus, the function F1 selects the ignition time correction amounts Δ θ a and Δ θ b so that the retard control is executed for some of the cylinders 1d and the advance control is executed for the other cylinders 1d among the cylinders 1d constituting the engine 1 during the period from the time t1 to the time t2 as described above.

More specifically, the control device 10 of the present embodiment executes the advance control in the #1 and #3 cylinders 1d of the engine 1, and executes the retard control in the #2 and #4 cylinders 1d of the engine 1, for example, during the period from the time t1 to the time t 2. In addition, the advance control may be executed in the #1 and #4 cylinders 1d of the engine 1, and the retard control may be executed in the #2 and #3 cylinders 1d of the engine 1. As a result, during the period from time T1 to time T2, the energy distribution η _ cw from the engine 1 to the coolant is increased compared to the engine 1 under the control of the control device of the comparative embodiment, and the coolant temperature T _ cw can be further increased at an early stage.

In the engine 1 under the control of the control device 10 of the present embodiment, as shown by the broken line in fig. 19 between the time T2 and the time T3, the catalyst temperature T _ cat exceeds the 3 rd threshold value T3 and the 2 nd threshold value T2, and the coolant temperature T _ cw is equal to or lower than the 1 st threshold value T1. Therefore, the function F0 of the control device 10 for distributing the ignition correction amount executes the process P37 shown in fig. 17 from the time t2 to the time t3, and sets the flag F to the mode M3 that gives priority to the heating of the cooling water.

Thus, the control device 10 of the present embodiment executes the process P48 shown in fig. 18 by the function F1 of calculating the ignition time correction amount Δ θ. Thus, the function F1 executes the advance control for all the cylinders 1d of the engine 1 as shown in the graph of the ignition time θ in fig. 19 during the period from the time t2 to the time t 3. As a result, during the period from time T2 to time T3, the energy distribution η _ cw from the engine 1 to the coolant is increased compared to the engine 1 under the control of the control device of the comparative embodiment, and the coolant temperature T _ cw can be further increased at an early stage.

Thereafter, as shown by the broken line in fig. 19 at time T3, the engine 1 under the control of the control device 10 of the present embodiment has the cooling water temperature T _ cw exceeding the 1 st threshold value T1. Therefore, the function F0 of the control device 10 for distributing the ignition correction amount executes the process P38 shown in fig. 17 after the time T3, and sets the flag F to the mode M4 for maintaining the cooling water temperature T _ cw and the catalyst temperature T _ cat.

Thus, the control device 10 of the present embodiment executes the process P49 shown in fig. 18 by the function F1 of calculating the ignition time correction amount Δ θ. Thus, function F1 sets ignition time correction amount Δ θ to zero after time 3. As a result, as shown in the graph of the ignition time θ of fig. 19, the ignition times θ of all the cylinders 1d of the engine 1 become the optimal ignition time θ o.

Next, the operation of the control device 10 of the present embodiment will be described.

As described above, when the catalyst temperature T _ cat is equal to or lower than the 3 rd threshold value T3 which is lower than the 2 nd threshold value T2, the control device 10 of the present embodiment increases the energy distribution η _ exh to the exhaust gas as compared with the energy distribution η _ cw to the cooling water in the catalyst warming control described above. With this configuration, when the temperature of the three-way catalyst 1h is lower than the predetermined 3 rd threshold value T3, the temperature of the three-way catalyst 1h can be rapidly increased with priority given to the warming-up of the three-way catalyst 1h, and the exhaust gas purification performance can be improved.

When the catalyst temperature T _ cat is higher than the 2 nd threshold value T2 and the cooling water temperature T _ cw is equal to or lower than the 1 st threshold value T1, the control device 10 of the present embodiment increases the energy distribution η _ cw to the cooling water in the cooling water heating control as compared with the energy distribution η _ exh to the exhaust gas. With this configuration, the temperature of the cooling water can be rapidly increased, and the efficiency of the engine 1 can be improved and the rapid use of heating can be realized.

Further, when the catalyst temperature T _ cat is equal to or lower than the 2 nd threshold T2 and the cooling water temperature T _ cw is equal to or lower than the 1 st threshold T1, the control device 10 of the present embodiment performs retard control on some of the cylinders 1d and advance control on the other cylinders 1d that constitute the internal combustion engine. With this configuration, the cooling water temperature T _ cw and the catalyst temperature T _ cat can be efficiently raised.

Further, in the case where the catalyst temperature T _ cat is equal to or lower than the 2 nd threshold T2 and the cooling water temperature T _ cw is equal to or lower than the 1 st threshold T1, the control device 10 of the present embodiment may alternately execute the retard control and the advance control in all the cylinders 1 d. More specifically, the retard control and the advance control may be switched once every predetermined number of cycles of the engine 1. With this configuration, the cooling water temperature T _ cw and the catalyst temperature T _ cat can be efficiently raised. Further, since the ignition timing θ is the same among the plurality of cylinders 1d, the control becomes easier than the case where the ignition timing θ is set in each of some of the cylinders 1d and the other cylinders 1 d.

The control device 10 of the present embodiment determines the retard correction amount of the retard control and the advance correction amount of the advance control so that the torques τ of all the cylinders 1d become equal. With this configuration, the operation of the engine 1 can be stabilized.

As described above, according to the control device 10 of the present embodiment, the catalyst temperature T _ cat can be quickly increased to the target temperature by setting the ignition timing correction amount Δ θ according to the states of the catalyst temperature T _ cat and the cooling water temperature T _ cw and switching between the advance control and the retard control of the ignition timing θ. By switching the distribution of the energy of the engine 1 in this way, it is possible to achieve both the improvement of the exhaust performance and the improvement of the heating performance due to the increase of the cooling water temperature. In the above-described embodiments, the example was described in which the ignition time θ was set so that the difference between the catalyst temperature T _ cat and the cooling water temperature T _ cw and the respective threshold values were correlated, but the advance limit value θ _ lim (-) and the retard limit value θ _ lim (+) may be set separately.

While the embodiments of the control device for an internal combustion engine according to the present disclosure have been described in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and they are included in the present disclosure even if there are design changes and the like without departing from the scope of the present disclosure.

Description of the symbols

1 … Engine (internal combustion engine)

1d … cylinder

10 … control device

P2 … treatment (control of cooling water heating and advanced control)

P5 … treatment (catalyst warming control, delay control)

P _ thr … throttle opening

T1 … threshold 1

T2 … threshold 2

T3 … threshold No. 3

T _ cat … catalyst temperature

T _ cw … Cooling Water temperature

Theta … ignition timing

θ _ lim (+) … retard limit

Theta _ lim (-) … advance limit value

Eta _ cw … energy distribution to cooling water

η _ exh … energy distribution to exhaust gases

Tau … torque.

Claims

1. A control apparatus of an internal combustion engine that acquires a cooling water temperature and a catalyst temperature of an exhaust system to control an ignition timing of the internal combustion engine, characterized by executing a cooling water warming-up control and a catalyst warming-up control,

the cooling water warming control is to increase an energy distribution from the internal combustion engine to cooling water when the cooling water temperature is a 1 st threshold value or less,

the catalyst warming control is to increase an energy distribution from the internal combustion engine to the exhaust gas when the catalyst temperature is equal to or lower than a 2 nd threshold value.

2. The control apparatus of an internal combustion engine according to claim 1,

an advance control that advances the ignition time is executed in the cooling water warming control,

a retard control that retards the ignition time is executed in the catalyst warming control.

3. The control apparatus of an internal combustion engine according to claim 2,

in the advance control, the more the difference between the 1 st threshold and the cooling water temperature increases, the more the advance correction amount for advancing the ignition time increases.

4. The control apparatus of an internal combustion engine according to claim 2,

in the retard control, the retard correction amount for retarding the ignition time is increased as the difference between the 2 nd threshold and the catalyst temperature is increased.

5. The control apparatus of an internal combustion engine according to claim 1,

when the catalyst temperature is equal to or lower than a 3 rd threshold value which is lower than the 2 nd threshold value, the energy distribution to the exhaust gas is increased in comparison with the energy distribution to the cooling water in the catalyst warming control.

6. The control apparatus of an internal combustion engine according to claim 1,

when the catalyst temperature is higher than the 2 nd threshold and the cooling water temperature is equal to or lower than the 1 st threshold, the energy distribution to the cooling water is increased in comparison with the energy distribution to the exhaust gas in the cooling water warming control.

7. The control apparatus of an internal combustion engine according to claim 2,

when the catalyst temperature is equal to or lower than the 2 nd threshold and the cooling water temperature is equal to or lower than the 1 st threshold, the retard control is executed for some of the cylinders and the advance control is executed for the other cylinders among the plurality of cylinders that constitute the internal combustion engine.

8. The control apparatus of an internal combustion engine according to claim 2,

the retard control and the advance control are alternately executed when the catalyst temperature is equal to or lower than the 2 nd threshold and the cooling water temperature is equal to or lower than the 1 st threshold.

9. The control apparatus of an internal combustion engine according to claim 7,

the retard correction amount of the retard control and the advance correction amount of the advance control are determined so that the torques of all the cylinders become equal.

10. The control apparatus of an internal combustion engine according to claim 3,

in the advance control, the advance correction amount is set to an advance limit value when the advance correction amount exceeds the advance limit value.

11. The control apparatus of an internal combustion engine according to claim 4,

in the retard control, the retard correction amount is set to the retard limit value when the retard correction amount exceeds the retard limit value.

12. The control apparatus of an internal combustion engine according to claim 10,

the advance limit value is set based on one of an ignition time at which abnormal combustion occurs in the internal combustion engine and an ignition time at which the total of the energy distribution to the drive system and the energy distribution to the coolant becomes maximum.

13. The control apparatus of an internal combustion engine according to claim 11,

the retard limit value is set in accordance with an ignition time at which a combustion state of the internal combustion engine becomes unstable.

14. The control apparatus of an internal combustion engine according to claim 2,

an advance limit value of the advance control and a retard limit value of the retard control are set according to a range in which rotation of the internal combustion engine can be continued.

15. The control apparatus of an internal combustion engine according to claim 2,

increasing a throttle opening degree of the internal combustion engine in a manner that compensates for a torque of the internal combustion engine that decreases due to the advance control or the retard control.